Roller bit



NOV. 24, 1936. c D 2,061,650

Filed Dec. 6, 1955 Away ,9 v

Patented Nov. 24, 1936 UNITED STATES PATENT OFFICE 7 ROLLER BITApplication December 6, 1933, Serial No. 701,142

18 Claims.

This invention relates to a well drilling tool and relates moreparticularly to a well drilling bit. A general object of this inventionis to provide a simple, practical and particularly efllcient roller bitfor use in the rotary method of well drilling.

Another object of the invention is to-provide a well'drilling bit thatis very rapid and effective in its cutting action or formationpenetrating action.

Another object of the invention is to provide a well bit embodying animproved form of roller cutter.

Another object of the invention is to provide a well bit embodying asimplified and effective means for dependably mounting a plurality ofroller cutters.

Another object of the invention is to provide.

a well bit including a plurality of roller cutters formed and positionedwith respect to one another to have zones or paths of active engagementwith the earth formation that occupy or cover the entire surface at thebottom of the well bore whereby the bit is smooth running and rapidandefiicient in operation.

Another object of the invention is to provide a novel roller cutterhaving an annular series of spaced cutting teeth whose length materiallyless than the length of the cutter, the said series being disposed sothat its teeth have cutting engagement with the earth formation from oneside to the other of the path of travel of the cutter during eachcomplete revolution of the cutter.

The teeth or the improved cutter provided by the invention are shortwith respect to the length of the cutter so that the driling pressure oractive feed pressure imposed on the teeth is materially increased perlineal unit of cutting edge making the cutter very rapid and efficientand the teeth are in a continuous annular series that is inclined oroblique with respect to the axis of rotation of the cutter and extendsfrom one end of the cutter to the other whereby the teeth have activeengagement with the earth formation throughout the width of the path oftravel of the cutter. Roller cutters must of necessity be ofconsiderable length to have bearings that are sufficiently long to belong wearing and where the individual teeth of a cutter extendthroughout its entire length, as is the usual practice, there is anappreciable difference in the distance and speed of travel of the innerand outer portions of the teeth which results in an undesirable draggingand scraping action. The individual teeth of the cutter provided by thisinvention are short with reference to the length of the cutter so thatthey do not have the undesirable scraping action of the long teeth ofthe typical roller cutters.

Another object of the invention is to provide a roller cutter of thecharacter mentioned above that operates without wobbling and withoutimparting an irregular motion to the bit.

Another object of the invention is to provide a roller cutter of thecharacter mentioned that may be easily and inexpensively manufacturedfrom cylindrical stock.

It is a further object of the invention to provide a roller bit of thecharacter mentioned that is simple and inexpensive of manufacture.

Other objects and features of the invention may become apparent from thefollowing detailed description of typical preferred forms andapplications of the invention, throughout which description referencemay be had to the accompanying drawing in which: I

Fig. l. is a longitudinal detailed sectional view of the bit provided bythe invention. Fig. 2 is a bottom elevation view of the bit. Fig. 3 isan enlarged side elevation of the two inner cutters apart from the bitshowing them in the positions they occupy with respect to one another.Fig. 4 is an end view of one of the cutters illustrated in Fig. 3. Fig.5 is a side view and end view of another form of cutter and Fig. 6 is aside elevation of still another form of cutter.

The well drilling bit provided by this invention includes generally abit head body iii, two bearing members or cutter carrying members ii andit on the lower end of the body, outer roller cutters A and B on themembers H and i2, respectively, and inner roller cutters C and D on themembers H and I2, respectively.

The bit head body ill is adapted to be operated on the lower end of astring of drill pipe and is provided at its upper end with suitablemeans for facilitating connection with the string. The particular bodyIll illustrated in the drawing has a shank portion l3 at its upper endprovided with a central screw threaded socket It for the reception ofthe pin of the drill collar or another part of the drilling string. Thelower portion or main portion l5 of the body i0 is widened in onedirectionbeing substantially rectangular in transverse cross section.Two sockets or recesses it are provided in the lower end of the body tohold or receive the cutters. The recesses i6 extend through the bodyportion i5 from one side to the other and leave two depending legs H atdiametrically opposite extremities of the portion it. The inner sides I8of the legs ii are preferably inclined downwardly and outwardly. Adownill) wardly projecting partition wall l9 separates the two recessesIS. The partition wall I9 is substantially vertical and is positioned atone side of the central longitudinal axis of the bit. Fluid passages orports 20 extend downwardly from the bottom of the socket H to the upperwalls of the recesses l6. There may be two spaced ports 20 dischargingdownwardly into each recess [6 to provide for the effective flushing ofthe two outters mounted in each recess.

The bearing members or cutter carrying members and I2 each rotatablysupport an outer roller cutter and an inner roller cutter. The members Hand 2 bridge or extend inwardly through the recesses |6 from the legs Hto points below the end of the partition wall l9. Each cutter carryingmember includes an outer portion 2| of comparatively large diameter tocarry an outer roller cutter and an inner portion 22 of reduced diameterto support an inner roller cutter. The members II and I2 are positionedso that their outer portions 2| are inclined downwardly and inwardly. Inthe particular assembly illustrated in the drawing the two portions 2|have the same inclination. The inner portions 22 of the cutter Icarrying members are stepped or offset downwardly so that outwardlyfacing shoulders 23 are provided at the inner ends of the portions 2|.The portions 2| of the cutter carrying members may seat in notches orrecesses in the lower ends of the legs l and may be welded to the legsas at 24. The inner portion 22 of the member II has its longitudinalaxis substantially normal to the central longitudinal axis of the bitwhile the inner portion 22 of the member l2 has a longitudinal axisinclined downwardly and inwardly toward the central axis of the tool.The inner portion 22 of the member |2 may have a smaller pitch orinclination than its outer portion 2|. As the inner portions 22 of thecutter carrying members are of reduced diameter inwardly facingshoulders 24 are provided on the members at the points of joinder of theportions 2| and 22. The inner ends of the portions 22 are received insockets in a block 26. The block 26 bears upwardly against the lower endof the wall i9 and is held against movement by dowel pins 27. The sideof the block 26 facing the recess l6 through which the member passes maybe substantially vertical while the opposite side of the block ispreferably inclined downwardly and outwardly to be substantially normalto the 1ongitudinal axis of the portion 22 of the member l2. A screw 28passes through a longitudinal opening 29 in the inner portion 22 of themember 8 and is threaded into a socket in the inner portion 22 of themember I2. The head of the screw 28 may be counter sunk in the outer endof the opening 29. The screw 28 effectively ties together or connectsthe members II and I2 and maintains them in their proper assembledrelation with the block 26. The manner of assembling the cutter carryingmembers II and I2 on the body ||l will be subsequently described.

The outer cutters A and B are provided to act on the side wall of thewell bore and the peripheral portion of the bottom of the bore. Theouter roller cutters A and B are rotatably mounted on the bearingportions 2| through bushings 30. Thrust washers 3| may be provided atthe outer ends of the bushings 30 and keys 32 may hold the washers andbushings against rotation. The bushings 30 are provided with outwardlyfacing annular shoulders 33 for engagement by opposing complementaryshoulders on the interiors of the cutters A and B whereby inward thrustsare effectively transmitted from the cutters to the bushings. The innerends of the bushings 30 are adapted to bear against the shoulders 23 ofthe members I and 2.

The cutters A and B, illustrated in the drawing, are cylindrical intheir general configuration and are provided with axial orlongitudinally extending peripheral cutting teeth 34. Due to thelocations of the cutters A and B and their downwardly and inwardlyinclined axes of rotation, the teeth 34 project outwardly beyond theouter sides of the legs l5 to have reaming engagement with the side wallof the well bore. The outer corners of the teeth 34 are preferablybeveled to be substantially vertical when the respective teeth are inactive cutting engagement with the formation. The outer cutters A and Bin being located at diametrically opposite sides of the bit, balance thebit during operation and their paths of travel or engagement with theformation, lap over one another. In practice the cutter B may beconsiderably shorter than the cutter A as illustrated in the drawing. Itis to be noted that the bushing 30 on the member covers the outer end ofthe opening 29 and, therefore, effectively prevents displacement of thescrew 28.

The inner cutters C and D are provided to act on the formation at thebottom of the well bore within the annular cut made by the outer cuttersA and B. Bushings 36 are provided on the bearing portions 22 of themembers II and I2 to rotatably carry the cutters C and D. The bushings36 have outwardly projecting thrust flanges engaging the shoulders 25.Thrust washers may be provided between the inner ends of the bushings 36and the block 26 and the bushings and washers may be held againstrotation by keys 31. The cutters C and D may be alike in shape or designas illustrated in Figs. 1 and 3 of the drawing. Each cutter C and Dincludes a body 40 having a central longitudinal bore or opening 4| forpassing a bushing 36. The ends 42 of the cutters are flat and normal tothe longitudinal axes of the bodies 40.

It is a feature of the invention that each cutter C and D has acontinuous circumferential series of spaced teeth which series lies in aplane that is oblique or inclined relative to the longitudinal axis ofthe cutter. The teeth 43 of the cutters C and D may be spiralled teethor may be longitudinally extending teeth. In the particular form of theinvention being described, the teeth 43 are longitudinal teeth extendingparallel with the longitudinal axis of'the cutter. The particular teeth43 illustrated in the drawing have fiat sides converging outwardly tolongitudinally extending cutting edges 44. It is an important feature ofthe invention that the teeth 44 are materially shorter than the bodies40 of the cutters, that is, the individual teeth 44 extend only a partor a fraction of the length of the cutter. In the particular cutters Cand D illustrated in the drawing the teeth 43 are approximately one-halfas long as the cutter bodies 40. The teeth 43 of each cutter are ofequal length and are arranged in a continuous series that is pitched sothat the teeth have active engagement with the earth formation from oneedge to the other of the path 01' the cutter during each completerevolution of the cutter. The ends of the teeth 43 are flat and paralleland lie in two parallel planes L obliquely disposed or inclined relativeto the axis of rotation of the cutter. The

planes L of the opposite ends of the series of teeth are disposedrelative to the axis of rotation of the cutter so that each plane Lintersects a continuation of the normal plane of an end of the cutterbody at the outer corner X of a tooth 43. The series of teeth 43arranged relative to the axis of the cutter as just describedextendsaround the cutter body 40 in diagonal relation thereto so thatthe teeth act throughout the width of the path of travel of the cutter.Fig. 3 of the drawing clearly illustrates the pitched or inclined seriesof teeth 43 of the two cutters C and D. The broken lines of Fig. 3illustrate the positions of the series of cutters 43 when the cuttershave each been turned one-half of a revolution from the rotativepositions illustrated by the full lines. The peripheries of the endportions 45 of the cutter bodies 40 may be slightly tapered inwardlytoward the opposite ends of the cutters.

The cutters C and D as rotatably mounted on the inner portions 22members II and I2 are positioned so that the teeth-43 of the cutter Dmake anannular out in the formation at the bottom of the bore whichextends inwardly from the inner edge of the annular cut made by theouter cutter A. The cutter C is positioned so that its teeth 43 make anannular cut in the earth formation at the bottom of the bore whichextends inwardly from the cut made by the cutter D to the center of thebore. From the above it will be seen that the cutters of the bit havepaths of active or cutting action which entirely occupy or cover thebottom of the well bore. As the teeth 43 of the inner cutters C and Dare comparatively short the downward feeding or drilling pressure isconcentrated at their cutting edges 44, there being a heavy drillingpressure per lineal unit of the short cutting edges 44 in engagementwith the earth formation. As the bit is rotated during drilling theseveral cutters rotate independently on their mountings and the teeth 43of the cutters C and D in being arranged in inclined series successivelycome into cooperation with different portions of the path taken by thecutters. In this manner the teeth 43 act on the formation throughout theentire widths of the paths of activity of the cutters C and D duringeach revolution of the cutters. The arrangement of the cutters 43 in theinclined series provides for an endwise or longitudinal sliding movementof the teeth 43 during their engagement with the earth formation whichhas a desirable freeing action when drilling in certain earth formations.

The cutters C and D may be made from cylindrical stock boredconcentrically to its longitudi- 1 nal axis. In making a cutter, theteeth 43 are first cut in the cylindrical body and the stock or body isset at the required angle for the turnirg down of the end portions 45 toleave the diagonal or inclined series of projecting teeth 43. The baseportions of the teeth turned down from the opposite end portions of thecutter may remain as ribs on the portions 45 as illustrated in Figs. 3and 4 of the drawing. V

In assembling the bit, the bushings 36 and the inner cutters C and D arefirst assembled on the inner portions 22 of the members H. The innerends of the cutter carrying members H and i2 are then fitted into theblock 26 and the members are securely connected by the screw 28. Theassemblies of the outer cutters A and B with their bushings, washers andkeys are then arranged on the outer portions 2| of the members II andI2.

The assembly of the two members H and I2 carrying the cutters is thenarranged on the lower end of the body 10 and the members II and H arewelded to the legs H. The block 26 is secured to the wall H! by thedowels 21. The cutter mounting assembly of the present inventiondependably and effectively supports the four outters for rotation and issuch that none of the parts can become loosened or displaced.

It is believed that the operation of the bit will be readily apparentfrom the foregoing detailed description. When the bit is attached to thelower end of a drilling string and rotated in the bottom of a well borein the usual manner the several cutters are independently rotatedthrough their engagement with the earth formation. The outer cutters Aand B are effective in cutting the outer or peripheral portion of thebottom of the bore and in reaming the side wall of the bore. The twocutters A and B positioned and operating as described above stabilizethe drill and provide for its smooth operation. The inner cutter Doperates to make an annular cut in the formation at the bottom of thebore that extends inwardly from the cut made by the cutter A. The cutterC makes an annular cut in the earth formation that extends outwardlyfrom the center of the bore to the cut made by the cutter D. The teeth43 of the cutter C and D are successively brought into engagement withthe earth formation and as they are short and have very limitedengagement with the formation, the drilling pressure or feeding pressureper lineal unit of cutting edge is great. This provides for the rapidand efiicient operation of the cutters. Further, the teeth 43 havelittle or no tendency to track or follow one another in their engagementwith the earth formation and have a desirable endwise movement whencontacting with the formation. The teeth 43 in being arranged ininclined series on the bodies of the cutters have active engagement withthe earth formation throughout the entire widths of the paths covered bythe cuttersr Fig. 5 of the drawing illustrates a cutter of a form thatmay be employed in the bit in place of the cutters C and D. The body 60of the cutter illustrated in Fig. 5 of the drawing is provided with acentral longitudinal bore 6i. An annular series of projecting teeth 62is provided on the cutter body 60. The series of teeth 62 is inclined oroblique relative to the longitudinal axis of the cutter. The ends of theteeth 62 lie in parallel planes which are inclined relative to the axisof the cutter so that each plane intersects the plane of an end of thecutter body at the outer corner of a tooth 62. The teeth 62 taperlongitudinally of the cutter and have cutting edges 63 which areinclined relative to the longitudinal axis of the cutter. The cuttingedges 63 are inclined outwardly toward the opposite ends of the cutter.The cutting edges 63 in being inclined as just described have limitedengagement with the earth formation and, therefore, are rapid andefficient in their cutting action. Theteeth 62 are preferably very muchshorter than the cutter body 60.

Fig. 6 of the drawing illustrates a form of cutter that is similar,generally, to the cutter illustrated in Fig. 5. The cutter shown in Fig.6 has a body 10 provided with a central longitudinal bore H. An annularseries of comparatively short teeth [3 projects from the body 70. Theseries of teeth 13 is oblique or inclined relative to the rotative axisof the cutter and its opposite ends lie in parallel planes. The cuttingedges 14 of the teeth I3 are pitched or inclined relative to the axis ofthe rotation of the cutter being pitched in the opposite direction tothe cutting edges 63 of the form of cutter illustrated in Fig. 5. Theinner points of the teeth l3 are the highest or outermost points of theteeth and thus have active cutting engagement with the earth formation.Due to the inclined relationship of the cutting edges H with the axis ofrotation of the cutter, the teeth have more limited engagement with theformation than the teeth of the cutters C and D described above.

In the cutter shown in Fig. 5 and the cutter shown in Fig. 6 the curvegenerated by the highest points or outermost points of the series ofcutting teeth is an ellipse so that the engagement of the teeth with theearth formation results in a lifting and falling motion of the cutter,the extent of this movement being dependent upon the pitch orinclination of the cutting edges of the teeth relative to the axis ofrotation of the cutter. It is believed that it will be apparent how theforms of cutters, illustrated in Figs. 5 and 6 of the drawing may beemployed in the bit in place of the cutters C and D, it being understoodthat the improved. cutters of the present invention are not to beconstrued as limited for use on the particular bit illustrated in Figs.1 and 2 of the drawing and described above.

Having described only typical preferred forms and applications of myinvention, I do not wish to limit myself to the specific details setforth, but wish to reserve to myself any changes or variations that mayappear to those skilled in the art, or that fall within the scope of thefollowing claims.

Having described my invention, I claim:

1. A well bit including a body having two recesses in its lower end,inclined members rigidly attached to the body and extending across therecesses, cutters in the recesses rotatable on the members, and meansconnecting the inner ends of the members, said means including a screwextending through an opening in one member and threaded into the othermember.

2. A well bit including a body having two recesses in its lower end, amember extending inwardly across each recess, each member having adownwardly and inwardly inclined outer bearing portion and an innerbearing portion of reduced diameter, means supporting the inner ends ofthe members against upward thrusts, roller cutters rotatable on theouter bearing portions for making an outer annular cut and for engagingthe side wall of the well bore, and roller cutters rotatable on theinner bearingportions for making annular cuts one within the other whichextend from the center of the bore to the first mentioned cut.

3. A well bit including a. body having two recesses in its lower end, amember extending inwardly across each recess, each member having adownwardly and inwardly inclined outer bearing portion and an innerbearing portion of reduced diameter, roller cutters rotatable on theouter bearing portions for making an outer annular cut and for engagingthe side wall of the well bore, and roller cutters rotatable on theinner bearing portions for making annular cuts one within the otherwhich extend from the center of the bore to the first mentioned cut, oneof said inner bearing portions being substantially normal to the axis ofrotation of the bit and the other inner bearing portion being inclineddownwardly and inwardly.

4. A well bit including a body having two recesses in its lower end, awall depending from the body and separating the recesses, membersattached to the body and extending inwardly across the recesses, eachmember having an outer bearing portion and a reduced inner bearingportion, roller cutters rotatable on the outer hearing portions, cuttersrotatable on the inner bearing portions, a block bearing upwardlyagainst the lower end of the wall and having sockets receiving the innerends of the members, and a connecting screw tying together the innerportions of the members.

5. A well bit including a body having two recesses in its lower end, awall depending from the body and separating the recesses, membersattached to the body and extending inwardly across the recesses, eachmember having an outer bearing portion and a reduced inner bearingportion, bushings on said portions, roller cutters rotatable on thebushings, a block bearing upwardly against the lower end of the wall andhaving sockets receiving the inner ends of the members, the outerbearing portion of one member beieng inclined downwardly and inwardlyand the inner bearing portion of said member being substantiallyhorizontal and having a longitudinal opening, and a screw passingthrough said longitudinal opening and threaded into the other member,the bushing on the inclined outer bearing portion covering the end ofsaid opening.

6. A well drilling bit including a body, outer cutting means on thelower end of the body for making an annular cut in the earth formation,and inner cutting means on the lower end of the body for cutting theformation within said an-- nular cut, the inner cutting means includinga rotatable roller cutter body, and an annular series ofcircumferentially spaced projecting teeth extending around the cutterbody, the teeth being materially shorter than the cutter body and thesaid series of teeth lying in a plane inclined relative to the axis ofrotation of the cutter body.

7. In a well drilling tool, a cutter comprising a body rotatable about alongitudinal axis, and cutting teeth projecting from the body, thecutting teeth being materially shorter than the body and being in anannular series within a zone which extends diagonally around the cutter.

8. A well bit including a body having two recesses in its lower end, amember extending inwardly across each recess, each member having adownwardly and inwardly inclined outer bearing portion and an innerbearing portion of reduced diameter, roller cutters rotatable on theouter bearing portions for making an outer annular cut and for engagingthe side wall of the well bore, and roller cutters rotatable on theinner bearing portions for making annular cuts one within the otherwhich extend from the center of the bore to the first mentioned cut,each of the last mentioned cutters having an annular series ofcircumferentially spaced teeth surrounding it, said teeth being shorterthan the cutter and lying within a zone or plane inclined relative tothe axis of rotation of the cutter.

9. A well drilling bit including a body, outer cutting means on thelower end of the body for making an annular cut in the earth formation,and inner cutting means on the lower end of the body for cutting theformation within said annular cut, the inner cutting means including arotatable roller cutter body, and an annular series of projectinglongitudinally disposed teeth extending around the cutter body, theteeth being shorter than the cutter body and the said series of teethlying in a zone inclined relative to the axis of rotation of the cutterbody.

10. A well drilling bit including a body adapted to be attached to theend of, a rotatable drilling string, and cutting means on the lower endof the body including a cutter mounted on the body for rotation, and aplurality of spaced-projecting cutting teeth on the cutter, the teethbeing materially shorter than the cutter and being in an annular seriesextending around the cutter and being within a zone or plane which isoblique relative to the axis of rotation of the cutter.

11. Awell drilling bit including a body adapted to be attached to theend of a rotatable drilling string, and cutting means on the lower endof the body including a cutter mounted on the body for rotation, and aseries of spaced projecting cutting teeth on the cutter, the teeth beingmate-- rially shorter than the cutter and lying within a zone whoseopposite axial extremities are delined by substantially parallel planesinclined relative to the axis of rotation of the cutter, said planesintersecting the planes of the opposite ends of the cutter at pointsadjacent the outer corners of teeth of the series.

12. A tool of the character described including a body to be rotated, aspindle member on the body having a longitudinal axis inclined withrespect to the axis of rotation of the body, and a cutter rotatable onthe spindle member and having a plurality of spaced projecting teeth,the

teeth being shorter than the cutter and being in an inclined serieswithin a zone which extends diagonally around the cutter.

13. A tool of the character described including a body to be rotated, aspindle on the body having a longitudinal axis angularly related to theaxis 01. rotation of the body, and a cutter rotatable on the spindle andhaving an annular series of spaced cutting teeth extending around it,the teeth being shorter than the cutter and lying within a zone or planeinclined relative to the axis of rotation of the cutter.

' the axis of rotation of the cutter, the teeth in 14. A roller cutterfor an earth boring tool including a body adapted for rotation, and anannular series of cutting teeth extending around the body, the teethbeing shorter than the body and lying within a zone or plane inclinedrelative to 6 the axis of rotation of the cutter.

15. A roller cutter for an earth boring tool including a body adaptedfor rotation, and an annular series of cutting teeth extending aroundthe body, the teeth being shorter than the body and 10 lying within azone or plane inclined relative to the axis of rotation of the cutter,the teeth having cutting edges extending substantially parallel withsaid axis.

16. A roller cutter for an earth boring tool ineluding a body adaptedfor rotation, and an annular series of cutting teeth extending aroundthe body, the teeth being shorter than the body and lying within a zoneor plane inclined relative to eluding cutting edges inclined relative tosaid axis.

1'7. A roller cutter for an earth boring tool including a body adaptedfor rotation, and an annular series of cutting teeth extending aroundthe body, the teeth being shorter than the body and lying within a planeobliquely disposed with respect to the longitudinal axis of the body,the teeth having cutting edges substantially normal to said plane.

18. A well boring tool including a body adapted to be rotated about asubstantially vertical axis,

a cutter located at one side of said axis and carried by the body forrotation about an axis substantially transverse of said axis, and anannular series of projecting circumferentially spaced teeth on thecutter, the teeth being shorter than the cutter and the said series ofteeth lying within 40 a zone which is oblique relative to the axis ofrotation of the cutter.

ALFRED C. CA'I'LAND.

